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    <title>Document</title>
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<body>
    <button class="div">点只因</button>
    <input type="text" value="古月方源">
    <div>马鸿运</div>
</body>
</html>
<script>
    var a= document.querySelector(".div")
    a.onclick=function(){
        console.log(999);
    }
    var b=document.querySelector('input')
    b.onfocus=function(){
        b.value='白凝冰'
    }
    b.onblur=function(){
        b.value='古月方源'
    }
    var m=document.querySelector("div")
    m.onclick=function(){
        m.innerHTML='鸿运齐天'
    }
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